1. **State the problem:** Calculate the circumference of a trundle wheel with diameter 40 cm. Calculate the length of the car park if the wheel rotates 85 times. Calculate how many rotations the wheel makes to measure a 10 m line. 2. **Formula for circumference:** The circumference $C$ of a circle is given by: $$C = \pi d$$ where $d$ is the diameter. 3. **Calculate circumference:** Given $d = 40$ cm, $$C = \pi \times 40 = 40\pi \approx 125.66 \text{ cm}$$ Rounded to the nearest cm: $$126 \text{ cm}$$ 4. **Calculate length of car park:** The wheel rotates 85 times, so total length $L$ is: $$L = 85 \times C = 85 \times 125.66 = 10681.1 \text{ cm}$$ Convert to meters: $$\frac{10681.1}{100} = 106.81 \text{ m}$$ Rounded to nearest meter: $$107 \text{ m}$$ 5. **Calculate rotations for 10 m line:** Convert 10 m to cm: $$10 \times 100 = 1000 \text{ cm}$$ Number of rotations $N$ is: $$N = \frac{1000}{C} = \frac{1000}{125.66} \approx 7.96$$ Rounded to nearest whole number: $$8$$ **Final answers:** - Circumference: 126 cm - Length of car park: 107 m - Rotations for 10 m line: 8